15
-27
6*1
-6 and -1.
The factor pairs of 36 are (36, 1) (18, 2) (12, 3) (9, 4) (6, 6) None of them add up to 9. If that was -36, you could use 12 and -3
-3 and -3
15
9
-27
15
The numbers that add to get 6 and multiply to get 81 are 3 and 3.
-9
6 and 1
26
24
-22
9 and 11.